The purpose of this grant is to study ultrastructural phenomena in a variety of subjects related to oral biology. The facilities are used by different investigators, independently and in collaborative research projects. Approaches include routine transmission electron microscopy, freeze-fracture-etch electron microscopy and scanning electron microscopy. The major areas of investigation are: 1. Study of the internal and surface characteristics of separated salivary gland cells maintained and stimulated under different tissue culture conditions. These experiments are integrated with studies relating to time-lapse motion picture analyses of secretion. 2. Studies concerning the formation and conservation of cell membranes and their changing characteristics with different phases of the secretory cycle in salivary glands. 3. Formation of bioadhesive substances by sea mussels; primarily the distal adhesive plaque which actually cements the mussel's threads onto external surfaces. 4. Effects of experimental malnutrition of organs such as salivary glands, liver, pancreas and brain. By restricting essential dietary components, altered physiometabolic pathways are reflected in the structural organization of different cells. 5. Studies of the surface characteristics of experimentally injured vascular walls. This is part of a collaborative study of the effects of age, diet and trauma in atherosclerosis.